High Performance Pyroelectric Detectors for Space-Based Instruments

Lead Organisation: Leonardo MW Ltd.
Project Lead: Keith Barnes

In response to the 10th Call for Earth Observation Technology and Instrument Development Proposals issued by the Centre for Earth Observation Instrumentation (CEOI), Leonardo MW Ltd. is proposing a technology development activity for enhanced performance uncooled pyroelectric detectors to be used in space-based EO instruments. The objective of this programme of work is to demonstrate a significant improvement in the detectivity of pyroelectric detectors through the use of an alternative material composition.

Leonardo holds a world-leading position in the development and manufacture of single element pyroelectric detectors using DLATGS for use in scientific instruments such as laboratory and hand held FTIR spectrometers for chemical analysis. The company’s pyroelectric detectors are also used in space, principally for thermal emission spectrometers on science and exploratory missions, including NASA’s Mars rovers and the recently launched OSIRIS Rex.

The DLATGS (deuterated L-alanine doped triglycine sulphate) material used by Leonardo has an inherently broad spectral response from 0.3μm to beyond 100μm which can be tailored through the choice of a suitable window material. Of particular interest to earth scientists is the far infrared region (15μm and greater) because it includes 50% of the Earth’s infrared energy emitted to space and contains most of the Earth’s water vapour greenhouse effect. However, it has never been measured spectrally in its entirety from space, due primarily to the technical difficulties associated with achieving the necessary instrument signal to noise across the region.

Two Earth observation missions being considered at present intend to make measurements in this region using the unique characteristics of DLATGS pyroelectric detectors. These are NASA’s CLARREO (Climate Absolute Radiance and Refractivity Observatory) mission and the ESA EE9 candidate mission, FORUM (Far-infrared-Outgoing-Radiation Understanding and Monitoring).

The baseline design for the FFTS (FORUM Fourier Transform Spectrometer) instrument uses optical concentrators to maximise the incident light coupled to the sensitive area of the detector element. Enhanced detector performance would enable greater degrees of freedom in the equipment design in terms of improved system detection sensitivity. This would allow more accurate scientific measurements, simplification of the optics, and help reduce payload size and mass as well as mitigate risks associated with optics design. This aligns with the stated theme of ‘New and innovative ideas for EO technology development’.  The FORUM mission could be the first use of Leonardo pyroelectric detectors in a space based FTIR instrument for an ESA earth observation mission. This would open the way to use this detector type for future ESA missions as well as for enhanced versions of the existing thermal emission spectrometers.

Like FORUM, the CLARREO science team includes UK institutions such as Imperial College, London. Therefore the return on this investment would be realised not only by Leonardo but also the UK science community through its access to state of the art technology applicable to these missions.